Method of producing crown caps



Dec. 14, 1937. sc 2,102,285 METHOD OF PRODUCING GROWN CAPS Fil d Jan. 8, 1937 Patented Dec. 14, 1937 PATET QFFICE METHOD OF PRODUCING CROWN CAPS Harry M. Schmidt, Chicago, Ill, assigner to Mitchell & Smith, Inc., Detroit, Mich, a corporation of Massachusetts Application January 8, 1937, Serial No. 119,638

2 Claims.

The present invention relates to a method of producing crown caps with a so-called spot at the sealing face.

Those skilled in the art are familiar with spot crowns which comprise the use of a disk of metal foil or treated paper adhering to the sealing cork insert at the interior of the crown and centered with respect to the crown in such a manner that the lip of the container surrounds the spot, but the latter completely protects the contents of the container from communication with the yielding cork material of the crown. These spots are normally produced by automatically removing disks from a sheet of foil and applying these disks with an adhesive substance in a predetermined location to the crown itself.

It is the object of the present invention to produce spot crowns by an entirely new and better procedure commonly employed With this general object in method than the for this purpose.

- view, I propose to form a spot of predetermined dimensions and location on the sealing face of the crown by applying to the crown within a circumscribed area a suitable plastic in the liquid phase, and thereafter by manipulation insuring that the plastic deposited shall maintain the circumscribed form and location.

In the accompanying drawing, Figs. 1 to 4, inclusive, illustrate somewhat diagrammatically the successive steps in the formation of the spot crown as I have developed it. v

In a simple and efficient embodiment of the invention as illustrated, the finished crown I8, except for the application of the spot, is clamped against the open end of a delivery tube l2 which is smaller in diameter than the face of the crown, and when in operative engagement therewith defines an area within which the spot is to be formed. The crown may be clamped against the open end of the tube in any desired manner, as by a holder M. With the crown held in an inverted position and clamped to the lower end of the tube, a solution of a plastic such as vinyl acetate or cellulose acetate in a solvent such as acetone, may be maintained in a liquid condition, and delivered from the tube in sufficient quantity to effectually coat the exposed face of the cap within the tube. Thereafter the relative position of the cap and tube is changed to cause removal by gravity of the surplus liquid plastic, leaving only a thin film engaging with the surface of the crown. Withdrawal of the tube from the end of the crown causes evaporation of the solvent and hardening of the plastic, particularly (Cl. l1380) if aided by a ventilated current of air or gas passed. thereover.

I have found it desirable to prevent accumulation of hardened plastic on the interior of the tube by providing a-clearing plunger or the like indicated at i 6, which slides within the tube with a sufiiciently close fit to shear off and remove particles of plastic, and which is of sufiicient weight to move toward and from the end of the tube by gravity as the position of the tube is reversed. This slide may be provided with a passage or orifice 18 extending therefrom to perunit the flow of liquid plastic.

Obviously my method is concerned with the application of the plastic in liquid form and the removal of surplus therefrom to control the deposit which remains in contact with the cap. Although forming no part of the present invention, it will be recognized that this may be readily accomplished by mounting a series of caps and delivery tubes upon a member revolving in a vertical plane which will successively carry the caps and tubes clamped thereagainst through the delivery phase and removal phase of the cycle.

I have indicated the use of vinyl and cellulose acetates as these materials represent plastics which can be satisfactorily handled in a solvent, and which when hardened by removal of solvent are impervious and inactive in contact with the usual contents of capped containersu Obviously other and similar plastics functioning in the same general manner could be substituted for those mentioned, if so desired.

This type of spot has many advantages in application, as the operation may be quickly and simply accomplished with a minimum of failures, and the resulting spot is a definite improvement upon the attached disk of foil or paper commonly used, as it offers greater insurance against rupture or leakage, and presents no opportunity for loosening or curling or fraying at the edges.

What is claimed is:

1. The method of providing sealing caps with an impervious facing, which consists in holding the sealing face of the cap in operative engagement with a hollow delivery tube which circumscribes the area of the facing to be applied, delivering to the exposed face of the cap within the tube a dissolved plastic in a liquid phase, and thereafter withdrawing the surplus of dissolved plastic while the cap is still maintained in operative relation to the delivery tube to leave the cap with a relatively thin residuum of plastic film which hardens and assumes solid form upon exposure to air.

2. The method of providing sealing caps with an impervious facing, which consists in holding the sealing face of the cap in operative engagement with a hollow delivery tube which circumscribes the area of the facing to be applied, de-

livering to the exposed face of the cap by gravity within the tube a dissolved plastic in a liquid 

